Method of operating a continuous ink jet printer apparatus

Abstract

A method of operating a continuous ink jet printer apparatus, the method comprising the steps of: applying a first voltage pulse to an electrode in order to modify the direction of an ink stream; applying a second voltage pulse to the electrode for a pre-determined period of time; measuring the charge carried on the ink stream; and modifying the operation of the printer in response to the charge measured.

1. A method of operating a continuous ink jet printer apparatus, the method comprising the steps of: applying a first voltage pulse to an electrode in order to modify the direction of an ink stream; applying a second voltage pulse to the electrode for a pre-determined period of time in order to detect the phase of the ink stream; measuring the charge carried on the ink stream; and modifying the operation of the printer in response to the charge measured. 
   
   
     2. A method according to  claim 1  wherein the timing and/or magnitude of the first voltage pulse is modified in response to the charge measured. 
   
   
     3. A method according to  claim 1  or  claim 2  wherein the second voltage pulse is positive. 
   
   
     4. A method according to  claim 1  or  claim 2  wherein the second voltage pulse negative. 
   
   
     5. A method according to  claim 1  or  claim 2  wherein the second voltage pulse is a half width pulse. 
   
   
     6. A continuous ink jet printer apparatus including circuitry for applying a first voltage pulse to an electrode in order to modify the direction of an ink stream, and for applying simultaneously a second voltage pulse to the electrode for a pre-determined period of time for detecting the phase of the ink jet stream. 
   
   
     7. A printer apparatus according to  claim 6  wherein said circuitry comprises an electrode driver, a phasing driver and a network comprising diodes and resistors, the drivers being electrically connected to the electrode via the network, the printer apparatus being operable: in a first state in which no signal is sent by either of the drivers and the ink jet stream is allowed to print onto a substrate; in a second state in which the electrode driver applies the first voltage pulse to deflect the ink jet stream into a gutter; and in a third state in which the electrode driver applies the first voltage pulse and the phasing driver applies the second voltage pulse for detecting the phase of the ink jet stream. 
   
   
     8. A printer apparatus comprising an electrode, first and second voltage sources and a resistor network, the electrode being electrically connected to the voltage sources via the resistor network, the printer apparatus being operable: in a first state by applying a low signal from the first and second voltage sources to the electrode; in a second state by applying a low signal from the first voltage source and a high signal from the second voltage source to the electrode; and in a third state by applying a high signal from the first and second voltage sources to the electrode. 
   
   
     9. A printer apparatus according to  claim 8  wherein: in the first state an ink jet stream associated with the electrode is allowed to print onto a substrate; in the second state the electrode is charged such that the phase of the ink jet stream can be detected; and in the third state the ink jet stream is deflected into a gutter.